MADISON, Wis. -- After an all-day public hearing, a state agricultural committee refused on Thursday to sign off on some rules aimed at keeping manure out of Wisconsin rivers and groundwater.

The senate Ag Committee voted to send back the controversial Department of Natural Resources rule NR 243 to the DNR board so farm industry concerns can be addressed.

The set of manure regulations has already been in the works for four years. They target so-called "Concentrated Animal Feeding Operations," or CAFOs -- the largest livestock operations in the state each capable of producing millions of gallons of concentrated liquid manure.

Backers of the rule said it's necessary to prevent pollution that kills fish and causes groundwater and well water contamination.

But CAFOs said the DNR is going too far with its proposed rules. Many cite one regulation that bans liquid manure spreading if the National Weather Service says there is a 70 percent chance of rain.

"There's no way at any time we can manage our crops and harvest according to the weather service report. So, it's important we keep common sense and focus here," said Jerry Meissner, of Norm-E-Lane Farms, which has 1,600 cows in Marshfield.

But one Lake Michigan resident said that in less than a year, her beachfront has changed into a year-round algae and she blames manure runoff from the livestock farms that moved into the area.

The revised DNR rules are prompted by new federal requirements. Some said NR 243 should simply mirror those requirements.

Others, including environmental groups, support NR 243 as is to limit what they contend is escalating manure contamination.

The proposed rules include a ban on liquid manure spreading during winter, and a minimum six months worth of storage.